(Pb,La)(Zr,Sn,Ti)O₃ (PLZST) antiferroelectric (AFE) materials have been widely investigated for advanced pulsed power capacitors because of their fast charge-discharge rates and superior energy-storage capacity. For practical applications, pulsed power capacitors require not only large energy density but also high energy efficiency, which are very difficult to achieve simultaneously. To address this problem, we herein investigate the energy-storage properties of PLZST AFE ceramics with a high Sn content by considering that the introduction of Sn can make the polarization versus electric-field (P-E) hysteresis loops slimmer. The results show that an optimum Sn content leads to the realization of both large recoverable energy density (W_re) and high energy efficiency (η) in a single material. With a Sn content of 46%, the PLZST AFE ceramic exhibits the best room-temperature energy storage properties with a W_re value as large as 3.2 J/cm³ and an η value as high as 86.5%. In addition, both its W_re and η vary very slightly in the wide temperature range of 20–120 °C. The high W_re and η values and their good thermal stability make the Pb_0.97La_0.02(Zr_0.50Sn_0.46Ti_0.04)O₃ AFE ceramic a promising material for making pulsed power capacitors usable in various conditions.

Dielectric nanocomposites composed of a polymer matrix with high electric breakdown strength and inorganic ferroelectric nanofillers with large maximum electric displacement (D_max) have recently attracted much attention due to their high power density, superior flexibility, and good fatigue endurance. However, their discharge energy density and energy efficiency are limited because of the high remnant displacement (D_r) and small D_max − D_r values of the ferroelectric fillers. Compared with ferroelectrics, antiferroelectrics exhibit much lower D_r (near zero) and far larger D_max − D_r values, and thus if they are used as the fillers of the dielectric composite, a larger discharge energy density and higher energy efficiency may be obtained simultaneously. Based on this, in this work, Pb_0.97La_0.02(Zr_0.50Sn_0.45Ti_0.05)O₃ (PLZST) antiferroelectric nanoparticles (∼200 nm in diameter) coated with a dense and robust dopamine layer are prepared in order to develop dopamine-modified PLZST filler/poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) polymer nanocomposites with superior energy storage properties. The experimental results indicate that optimizing the filler content leads to a small D_r (0.61 μC cm⁻²), large D_max − D_r value (6.14 μC cm⁻²), and high electric breakdown strength (3136 kV cm⁻¹), as a result of which, the PLZST/P(VDF-HFP) nanocomposites filled with 5 wt% dopamine-modified PLZST nanoparticles simultaneously exhibit a large discharge energy density of 9.39 J cm⁻³ and high energy efficiency of 82%. These energy storage properties are superior to those of most ferroelectric filler (including nanowires and nanofibers prepared by complicated methods)/polymer nanocomposites with a single-layer structure. Our work not only proves that, antiferroelectric nanoparticles are excellent fillers that can be comparable to, or even better than, ferroelectric nanowires and nanofibers prepared by very complicated methods, for energy-storage inorganic/polymer dielectric composites, but also provides a convenient and effective way to prepare and design flexible dielectric capacitors with superior energy storage capacity.

Polyetherimide nanocomposites with core–shell structured (Pb, La)(Zr, Sn, Ti)O ₃ @Al ₂ O ₃ antiferroelectric nanoparticle fillers deliver an ultra-high discharged energy density of 10.2 J cm ⁻³ and a large efficiency of 83.5% at 150 °C.

Dielectric polymer capacitors suffer from low discharged energy density and efficiency due to their low breakdown strength, small dielectric constant and large electric hysteresis. Herein, a synergistic enhancement strategy is proposed to significantly increase both breakdown strength and dielectric constant while suppressing hysteresis, through introducing 2-dimensional bismuth layer-structured Na_0.5Bi_4.5Ti₄O₁₅ micro-sheets and designing a unique bilayer structure. Excitingly, an ultra-high discharged energy density of 25.0 J cm⁻³ and a large efficiency of 81.2% are achieved in Na_0.5Bi_4.5Ti₄O₁₅-poly(vinylidene fluoride-co-hexafluoropropylene)/Na_0.5Bi_4.5Ti₄O₁₅-polyetherimide bilayer composites under a dramatically enhanced breakdown strength of 8283 kV cm⁻¹. Finite element simulations along with experimental test results demonstrate that greatly improved breakdown strength is ascribed to uniform and horizontal alignments of Na_0.5Bi_4.5Ti₄O₁₅ sheets (~1–2 μm) in the matrix and interface effect of adjacent layers with large dielectric differences, which effectively inhibit electrical tree evolution and conduction loss. This work provides a strong foundation for developing high-performance polymer-based energy storage devices.

The low dielectric constant, limited breakdown strength, and large polarization hysteresis and conduction loss constrain discharged energy density and efficiency of polymer-based dielectric capacitors at elevated temperatures. To address these challenges, the [0.8(Na_0.2Bi_0.2Ba_0.2Sr_0.20Ca_0.2)TiO₃-0.2NaNbO₃]@Al₂O₃ high-entropy ferroelectric nanoparticles/polyetherimide-AlN/polyetherimide-triptycene bilayer nanocomposites are designed. The bilayer nanocomposites capitalize on advantages of high-entropy ferroelectric fillers, which contribute to the high dielectric constant and minimal hysteresis at high temperatures. Additionally, they also benefit from high thermal conductivity of AlN, enhanced rigidity and charge carrier traps in polyetherimide-triptycene, and suppressed carrier transport at the bilayer film interfaces. Consequently, the bilayer nanocomposites exhibit significantly improved dielectric constant and breakdown strength, and marked reduction in conduction loss at elevated temperatures. Remarkably, a record-high discharged energy density of 12.35 J cm⁻³ is achieved in the optimized bilayer nanocomposites at 150 °C, accompanied by a large efficiency of 90.25% under an electric field of 6341 kV cm⁻¹.